Geometric design for a poster



FIG. 1 is a front elevational view of a geometric design for a poster showing my new design;

FIG. 2 is a front elevational view of an element of the geometric design, shown separately for clarity of illustration; and,

FIG. 3 is a front elevational view of an element of the geometric design, shown separately for clarity of illustration.

The rear of the poster placard is flat and unornamented and forms no part of the claimed design. 

The ornamental design for a geometric design for a poster, as shown and described. 